To produce a highly polished appearance on the surface of manufactured articles, thin chrome layers have been applied onto the surfaces of articles using electroplating or vacuum deposition methods. These methods, however, have significant disadvantages. Mechanical polishing of the surface of a manufactured article is generally necessary prior to the application of the chrome layer. The process of mechanical polishing can be very expensive. In addition, chrome electroplating is a multi-step process involving the use of environmentally hazardous ingredients like hexavalent chromium and cyanides.
U.S. Pat. No. 5,656,335 describes a process for coating a substrate with a metal giving a polished effect. The process consists of (1) cleaning or powder coating the surface of the substrate, (2) coating the surface with metal by plasma deposition in vacuum chamber, and (3) top coating the metal coated substrate with powder lacquer. The metal applied by plasma deposition may be aluminum, chromium, titanium, silver or gold. The powder lacquer top coat is applied directly to the metal layer. In an optional process step, a carbon compound that is highly resistant to scratching may be applied to the top coat.
U.S. Pat. No. 6,068,980 describes a method for gloss coating articles that includes the steps of (1) applying a chromate layer onto the surface of the substrate; (2) applying a powdered paint layer to the chromate layer, (3) applying a corrosion inhibiting base coat to the powdered paint layer; (4) applying a high gloss metal layer using a magneto in a vacuum to the corrosion inhibiting base coat and (5) applying a transparent wear-resistant top coat to the high-gloss metal layer. The corrosion inhibiting base coat is disclosed as being made for example from a powdered baking finish or a sputtered paint and applied in a known fashion. The top coat is disclosed as being an organic-inorganic compound such as organically modified ceramic (ORMOCER), or an organic coating based on acrylates, polyurethane or epoxy resin. The gloss of the top coat may be adjusted with pigments.
The thin metal layer used to produce the polished effect in the prior methods is protected from the environment by only the top coat. In general, the topcoat is a transparent paint with a thickness up to 100 microns. The top coat does not provide adequate corrosion protection to the underlying metal layer.